The present invention is concerned with fluid flow concentrating devices and in one of its aspects with a wind concentrating device in the form of a vortex generator of the tornado-type.
It is known from U.S. Pat. No. 4,070,131 to provide a device in which atmospheric wind is admitted into a vertically extending open ended structure which is spaced from the ground or connected to a subterranean ram-air tunnel. The admitted wind is directed against the interior curved surface of the structure and provides a vortex flow and this flow provides a corresponding low pressure core which draws the air into the bottom of the structure to drive a horizontal turbine. Other fluid flow devices of the prior art are to be seen in U.S. Pat. Nos. 4,236,866; 4,142,822; 4,269,563; 4,260,325 and 1,519,447. Other wind augmentation types of devices are also in experimental use, these fall broadly into the categories of "duct augmentor turbines" and "tip vane turbines". The devices of the prior art have been useful for particular applications but are limited in their scope of application.